Where is the demo blend? I do not see it. I’m interested to see that too.
Quite a large file. I do not think that I really need that many data :D. I’m going to check it …
@Monster: Good luck 
If you find how to reproduce the bug in a simpler way, could you share your simplified .blend here: https://developer.blender.org/T46698 Thanks!
Lets hope we can get this bug fixed, im shocked no body else has come across this yet.
I updated the bug report.
Wow nice work Monster. It’s weird I can’t see delay before 2.72b… Maybe there is a little delay on my computer but I’m not sure… I’ll try to make a git bisect to see what commit causes the big difference beetween 2.71 and 2.72 on my computer. There’s a chance that it is the same part of the code that causes the delay on your computer beetween 2.68a and 2.69…
Eh, it’s very weird, ChaosEmergency said that was working in 2.75 ??
2.75 seems to have no delay, i`m using that blender atm while i wait for the bug to be fixed.
Ok I’ve tested the blend file.
I think, this bug has nothing to do with the object parenting, it’s somehow connected to the IK solver or bone -> follow object IK controller. The bug appears when you are trying to change the bone transformation with IK follow object set in it.I’ve experienced this also in Blender 2.49b.(In my game, when the character is moving his head toward an object I use IK bone transformation and the same thing is happening but it is almost unnoticeable and its ok in my case.)
I add a comment on https://developer.blender.org/T46698. Also a blend file(modified Chaos blend) with the bug in progress.
If you set 10fps you can see it.
The demo blend at the bug report shows two bars. One with armature deform (skin= blue bar) one with bone parenting (=red bar).
The armature turns the last bone which makes both bars turn too. When playing you can see they do not align to each other as they should. I tested in various versions. all my 2.7x versions have the same issue.
The demo file does not contain IK resolvers. I thought about the bone constraints too. But I think that would delay the bones of the upper bode as well. So it would be a delay … but not noticeable.
@Monster and @ChaosEmergency: So the Tristan’s patch doesn’t solve the problem for you (I tested with the file you shared Monster and it worked for me)?